The renal arteries carry a large portion of total blood flow to the kidneys. Up to a third of total cardiac output can pass through the renal arteries to be filtered by the kidneys.

Structure

It has a radius of approximately 0.25cm,[1] 0.26cm at the root.[2] The measured mean diameter can differ depending on the imaging method used. For example, the diameter was found to be 5.04 ± 0.74mm using ultrasound, but 5.68 ± 1.19mm using angiography.[3][4]

Due to the position of the aorta, the inferior vena cava, and the kidneys in the body, the right renal artery is normally longer than the left renal artery.[5][6]

Branches

Before reaching the hilus of the kidney, each artery divides into four or five branches; the greater number of these (anterior branches) lie between the renal vein and ureter, the vein being in front, the ureter behind, but one or more branches (posterior branches) are usually situated behind the ureter.

One or two accessory renal arteries are frequently found, especially on the left side since they usually arise from the aorta, and may come off above (more common) or below the main artery. Instead of entering the kidney at the hilus, they usually pierce the upper or lower part of the organ.

Variation

The arterial supply of the kidneys is variable and there may be one or more renal arteries supplying each kidney. It is located above the renal vein. Supernumerary renal arteries (two or more arteries to a single kidney) are the most common renovascular anomaly, occurrence ranging from 25% to 40% of kidneys.

Clinical significance

Renal artery stenosis, or narrowing of one or both renal arteries will lead to hypertension as the affected kidneys release renin to increase blood pressure to preserve perfusion to the kidneys. RAS is typically diagnosed with duplex ultrasonography of the renal arteries. It is treated with the use of balloon angioplasty and stents, if necessary.

Atherosclerosis can also affect the renal arteries and can lead to poor perfusion of the kidneys leading to reduced kidney function and, possibly, renal failure.

Additional images

The posterior surfaces of the kidneys, showing areas of relation to the parietes.